Shape reconstruction of axisymmetric Taylor bubbles using conductivity probes through a scheme of combined experiment and theory.

A simple measurement scheme is proposed to reconstruct the geometry of an axisymmetric void propagating through a conducting liquid using a pair of parallel wire conductivity probes. An experimental study allows for obtaining the time variation of the resistance of the film surrounding the void. Analytical modeling and numerical simulation has been adopted to correlate the resistance between the wire electrodes and the film thickness. Finally, the shape of the void can be estimated by combining the predicted resistance-film thickness relationship and the measured time variation of resistance. For validation, this scheme has been used to reconstruct the shape of a rising Taylor bubble. There is a fair match between the reconstructed shape of the bubble and its photographic image. The probable errors in the measurement scheme have been discussed and assessed mathematically.

Source and respiratory deposition of trace elements in PM2.5 at an urban location in Dhaka city.

Air pollution has been creating severe environmental crises in Dhaka. This city ranks at the top among the major cities of the world. A multidimensional study is needed to assess the severity of this crisis. This study aims to determine the sources of trace elements in PM2.5 and their effects on health. We measured concentrations of 15 trace elements in PM2.5 every hour for eight days using a well-equipped mobile air quality monitoring system integrated with an automatic sampling system (AQMS, Horiba, Japan). We analyzed the concentrations of the trace elements to identify their potential sources and diurnal variation and to compute the respiratory deposition dose of the trace elements to estimate the health risks they pose. The daily average concentration of PM2.5 was higher than the allowable limit set by the World Health Organization (WHO). Among the trace elements, sulfur had the highest concentration and vanadium was the lowest. We found out that concentrations of the elements were the highest during the middle of the day and the lowest during midnight. Four source profiles of PM2.5 were identified by positive matrix factorization (PMF). Soil dust with sulfur-rich petroleum contributed about 65 %, industrial and non-exhaust emissions about 5 % each, and heavy engine oil combustion about 25 % to air pollution. Air mass backward trajectory analysis indicated that Dhaka's air contains both local and transboundary pollution. According to the determined respiratory deposition dose of the elements, males had higher deposition than females during heavy exercise. Sulfur and vanadium have the highest and lowest respiratory deposition dose, respectively. The highest amount of deposition occurred in the upper airways. We expect that this study will help professionals develop effective strategies to prevent and mitigate the emission of air pollutants.

The Detection of Self-Similar/Branching Processes in Complex Biological Systems: Analysis of the Temporal Evolution of Impedance Measurements in Tulsi (Holy Basil) Leaves "Ocimumtenuiflorum".

In this paper, a theoretical model has been proposed for the first time to illustrate the living Tulsi (Holy Basil) leaf evolution in describing the branching systems in the intermediate range of frequencies. The proposed fitting function following the applied model portrays the whole stages of the temporal evolution of Tulsi (Holy Basil, "Ocimumtenuiflorum") leaf during the six days of impedance measurements with a high degree of accuracy (with fitting error less than 0.1 percent). The developed fitting parameter enables to identify the three stages of temporal evaluation of the Tulsi leaf as "vital leaf activity" (first stage), "quasi-chaotic behaviour" (second stage), and the "dying" (third stage). The theoretical model proposed in this work incorporated a fractal element having complex conjugated power law of exponents and a fractal element with a time lagged branching process. This novel approach introduces an additional degree of freedom over the previously proposed impedance models in terms of its imaginary part of complex conjugated power-law exponent. Further, it increases flexibility and versatility in accurately modeling the behavioral variations of complex branching systems, whose seemingly nondeterministic temporal nature had been considered earlier as counterintuitive and random. The incorporation of branching processes in comprehensively explaining the complex biological systems allows us to gain a deeper insight into the transfer of charge processes in the intermediate range of available frequency scales. Furthermore, the proposed model validates the presence of new fractal elements with a complex conjugated power law of exponents in naturally occurring biological processes. The experimental confirmation can play a key role in explaining a wide class of branching processes in complex systems and enrich the modern theory of fractional calculus.

Assessment of genetic divergence through cluster analysis of chilli varieties.

Our study on genetic diversity was conducted with six chilli genotypes with inter- and intra-specific cross varieties of the three most popular chilli species (Capsicum annuum L., Capsicum chinense Jacq., and Capsicum frutescens L.). Twelve quantitative characters, viz. plant height (cm), primary branches, secondary branches, number of flowers, number of fruits/plant; dry fruit weight (g), fruit length (cm), fruit diameter (cm), pedicel length (cm), pericarp thickness (mm), seeds/fruit, and seed weight (g), were taken into consideration. The analysis of variance revealed considerable variability among the genotypes for the character studied. Cluster analysis was used for grouping of parental and hybrid chilli genotypes under the study grouped into five clusters. Cluster I had the maximum (12) and clusters IVand V had the minimum number (1) of genotypes. The inter-cluster D2 values ranged between 40.404 and 127.530. The minimum inter-cluster distance was between clusters III and IV (40.404). The maximum inter-cluster distance was observed between clusters II and V (127.53). Diversity pattern and other horticultural performance among the genotypes of new varieties were generated due to the cross between Local Line Mahadev Pramanick and Sukhia bullet and also the cross between Local Line Mahadev Pramanick and Habanero orange (cluster II) as well as single parental variety i.e. Habanero orange. These genotypes were identified as promising varieties with respect to various characters may be taken into consideration as better parents for an efficient hybridization programme of chilli.

Bioimpedimetric analysis in conjunction with growth dynamics to differentiate aggressiveness of cancer cells.

Determination of cancer aggressiveness is mainly assessed in tissues by looking at the grade of cancer. There is a lack of specific method to determine aggressiveness of cancer cells in vitro. In our present work, we have proposed a bio-impedance based non-invasive method to differentiate aggressive property of two breast cancer cell lines. Real-time impedance analysis of MCF-7 (less aggressive) and MDA-MB-231 cells (more aggressive) demonstrated unique growth pattern. Detailed slope-analysis of impedance curves at different growth phases showed that MDA-MB-231 had higher proliferation rate and intrinsic resistance to cell death, when allowed to grow in nutrient and space limiting conditions. This intrinsic nature of death resistance of MDA-MB-231 was due to modulation and elongation of filopodia, which was also observed during scanning electron microscopy. Results were also similar when validated by cell cycle analysis. Additionally, wavelet based analysis was used to demonstrate that MCF-7 had lesser micromotion based cellular activity, when compared with MDA-MB-231. Combined together, we hypothesize that analysis of growth rate, death resistance and cellular energy, through bioimpedance based analysis can be used to determine and compare aggressiveness of multiple cancer cell lines. This further opens avenues for extrapolation of present work to human tumor tissue samples.

Wavelet-based multiscale analysis of bioimpedance data measured by electric cell-substrate impedance sensing for classification of cancerous and normal cells.

The paper presents a study to differentiate normal and cancerous cells using label-free bioimpedance signal measured by electric cell-substrate impedance sensing. The real-time-measured bioimpedance data of human breast cancer cells and human epithelial normal cells employs fluctuations of impedance value due to cellular micromotions resulting from dynamic structural rearrangement of membrane protrusions under nonagitated condition. Here, a wavelet-based multiscale quantitative analysis technique has been applied to analyze the fluctuations in bioimpedance. The study demonstrates a method to classify cancerous and normal cells from the signature of their impedance fluctuations. The fluctuations associated with cellular micromotion are quantified in terms of cellular energy, cellular power dissipation, and cellular moments. The cellular energy and power dissipation are found higher for cancerous cells associated with higher micromotions in cancer cells. The initial study suggests that proposed wavelet-based quantitative technique promises to be an effective method to analyze real-time bioimpedance signal for distinguishing cancer and normal cells.

A low cost instrumentation system to analyze different types of milk adulteration.

In this paper, the design of a complete instrumentation system to detect different types of milk adulteration has been reported. A simple to use indicator type readout device is reported which can be used by milk community people. A low cost microcontroller based automatic sensing system is also reported to detect 'synthetic milk', which has been reconstructed after adulterating the milk with 'liquid-whey'.

A microfluidic device for continuous manipulation of biological cells using dielectrophoresis.

The present study demonstrates the design, simulation, fabrication and testing of a label-free continuous manipulation and separation micro-device of particles/biological cells suspended on medium based on conventional dielectrophoresis. The current dielectrophoretic device uses three planner electrodes to generate non-uniform electric field and induces both p-DEP and n-DEP force simultaneously depending on the dielectric properties of the particles and thus influencing at least two types of particles at a time. Numerical simulations were performed to predict the distribution of non-uniform electric field, DEP force and particle trajectories. The device is fabricated utilizing the advantage of bonding between PDMS and SU8 polymer. The p-DEP particles move away from the center of the streamline, while the n-DEP particles will follow the central streamline along the channel length. Dielectrophoretic effects were initially tested using polystyrene beads followed by manipulation of HeLa cells. In the experiment, it was observed that polystyrene beads in DI water always response as n-DEP up to 1MHz frequency, whereas HeLa cells in PBS medium response as n-DEP up to 400kHz frequency and then it experiences p-DEP up to 1MHz. Further, the microscopic observations of DEP responses of HeLa cells were verified by performing trapping experiment at static condition.